Two years of on-farm trials at seven central Illinois and western Indiana locations found nearly all Illinois growers would probably benefit from planting soybean cyst nematode (SCN)-resistant soybean varieties. Many growers have been hesitant to plant resistant varieties because of the potential for so-called yield drag.
According to Greg Noel, USDA nematologist in the Department of Crop Sciences at the University of Illinois (U of I), probably few fields in Illinois are without at least some cyst nematodes. He says that planting resistant varieties most often paid off in fields with low levels of SCN infestation. He also notes growers can have yield losses as high as 10 to 15% from nematodes in fields where there are no outward signs of damage.
Noel suggests that growers with any history of SCN problems plant SCN-resistant varieties. Even those with no clear signs of a problem also should strongly consider planting a resistant variety as a form of no-cost insurance.
“Although yield drag does occur in fields with zero or low nematode populations, the problem is trying to determine whether or not you have a low population,” Noel says. “The troubling thing is that you can have a fairly significant yield loss from SCN and not even know you have it. In those cases, a resistant variety would certainly pay off in higher yields.”
The Varietal Information Program for Soybeans (VIPS) maintained at the U of I is a database providing unbiased information about soybean varieties from a range of companies. This database includes evaluations of resistance against various nematode populations. The varieties entered in the trials were tested at 13 different sites around the state of Illinois. There were 134 conventional varieties and 661 Roundup-resistant varieties from 70 companies tested in the 2003 soybean trials. Noel advises growers to use this database to help make an informed decision about what specific varieties to plant.
Information from the VIPS database is available at www.vipsoybeans.org .